This invention relates generally to the production of batteries during the neutralization, forming and charging stages, and more particularly, to a formation tub utilized in this process.
One problem often encountered in the battery industry relates to the control of temperature and time of battery formation. When electrolyte is first added to a previously unfilled, unformed battery it interacts with the paste on the plates contained within the battery, and a great deal of heat is generated. This heat is referred to as the heat of neutralization. Heat continues to be generated by the battery during the formation and charging process, particularly while a high current flow is present through the batteries. While it is possible to control the heat generated by using lower current rates, it is uneconomical to purchase and maintain sufficient equipment to form batteries at a current low enough to prevent this heating of the batteries.
Because of the heat generated during formation, a great deal of acid passes from the batteries into the surrounding atmosphere, creating an uncomfortable and corrosive environment. This is particularly true where, for economic reasons, a large number of batteries are being formed simultaneously in a minimum amount of forming room floor space. In addition, internal overheating of the batteries, if not properly controlled, can result in the damage or destruction of the battery.
Various means have been devised to cool batteries during the neutralization, formation, and charging process in order to avoid internal overheating of the batteries. The problem of dissipating heat which is generated during the formation of a battery has been aggravated by the widespread use of plastic battery cases throughout the automotive battery industry. Unlike rubber, composition, or glass cases previously used by the industry, plastic cases tend to have a low heat transfer coefficient which tends to insulate the interior of the battery, making it particularly susceptible to overheating problems.
Several approaches, such as circulating water baths in which batteries stand in rows of tanks permanently erected on the floor of the forming room, have been used in attempts to dissipate the heat produced when using high current during the battery neutralization, formation and charging process. While this has been successful, it is a highly restrictive technique and does not allow individual rectifying circuit control for batteries at various stages of neutralization, formation and charging.
Due to the relatively higher volumes of batteries produced, the use of plastic case designs and the various grid alloys and oxide mixtures now commonly used in the production of batteries, such prior art techniques have not proved satisfactory, and relatively long formation times have, therefore, been necessitated to insure that overheating does not occur during formation.
U.S. patent application Ser. No. 866,301, filed Jan. 3, 1978, now abandoned discloses an apparatus which is useful in overcoming the above described problems. In its preferred embodiment, the apparatus comprises a container means for holding a plurality of batteries in a pool of cooling fluid, such as water, which partially surrounds the batteries. The batteries are electrically connected in series within the tub and are adapted to be connected to a single charging circuit for each tub of batteries. The apparatus further comprises a transport means for facilitating transportation of the container means with the batteries therein, and for adapting the container means for stacking in a vertical array.
In the preferred embodiment, the tub is made of molded plastic and comprises a flange along each side of the tub. At least a portion of the flange acts as a lip means for engaging the transport means. The transport means is a metal frame having a plurality of vertical posts at each of the corners of the frame, the posts being connected by side members which receive the lip means or flange of the tub for aligning the tub within the frame. The frame also comprises a plurality of parallel, spaced transverse members located in a plane below the bottom of the tub for supporting the tub, and adapted to be engaged by a transportation mechanism such as a forklift truck for lifting the frame (with the tub and batteries) to stack it in a vertical array, or to move it to another part of the forming room floor.
In order to facilitate the stacking of the frames, one on top of the other, each post includes a tapered portion at one end which is adapted to engage hollow portions located at the other ends of the posts of a second frame which is to be placed above the first frame.
Each tub is filled with water when the forming process begins. This can be accomplished by filling the first tub with cooling fluid to a certain predetermined level, at which point the fluid is then allowed to overflow through an overflow opening or hole in the side of the tub, and from there, into the next lower adjacent tub. This process is repeated until the last tub is filled. At this point, the water overflows onto the forming room floor and is carried off to a cooling tower as described in U.S. Pat. No. 4,117,387. Alternatively, each of the tubs could be filled independently, or overflow could take place between two or more tubs with the overall array being filled at a number of places in the array. A variety of tub filling techniques may be used if desired.
Such an apparatus serves well in the formation of a maximum number of batteries in the minimum amount of forming room floor space. In addition, this apparatus greatly reduces the hazards attributable to the corrosive acid atmosphere which generally accompanies the formation of a large number of batteries in a single forming room. As the acid entrained atmosphere rises from the battery filled tubs, it impinges the bottom of the next higher tub whereupon it condenses and drips back into the lowermost tub. In this way, a large amount of the gases rising from the batteries being formed are captured by the apparatus and returned to the tubs. The cooling fluid, which comprises mainly water in the preferred embodiment, can be neutralized on its way back to the cooling tower. This apparatus, then, in addition to providing an economical way of forming a maximum number of batteries in a minimum amount of floor space, also serves to minimize adverse environmental impacts as a result of the formation process.
Although well adapted to its purpose, such an apparatus is still capable of further improvement. For example, the apparatus described is assembled from a combination of discrete components, each of which is constructed from one or more different materials. As a result, use of the apparatus requires prior assembly of its components. Moreover, such components must be properly aligned to assure proper operation. Each of these factors introduces a possibility for error in the system, as well as contributing to increased costs.
It, therefore, becomes desirable to develop a formation tub which eliminates one or more of these potential drawbacks.